A Mechanicsville woman who lost her job as a school bus driver last December, after police charged her with attempting to drive while impaired by alcohol while transporting a minor, pleaded guilty Wednesday and was released to await her penalty.

Ethel Quade Ressler, now 69, was arrested on the afternoon of Dec. 13 after law officers were called to Leonardtown High School, found her in a parked school bus with its motor running, and “detected a strong odor of an alcoholic beverage,” St. Mary’s Assistant State’s Attorney Jaymi Sterling said at Ressler’s plea hearing.

“She did admit to having a glass and a half of wine at lunch,” the prosecutor said.

A breath test at the sheriff’s office was inconclusive, the prosecutor said, but when Ressler was taken to MedStar St. Mary’s Hospital on an emergency petition, a blood sample was taken and revealed she had a blood-alcohol level of 0.19 percent.

The St. Mary’s sheriff’s office reported after the incident that the public school system’s transportation department received a complaint that day that the bus, carrying no students at that time, was being driven in a reckless manner, before it was found parked at the school in Leonardtown with about 12 students getting on board. After Ressler was taken into custody, another driver and bus were called in to transport the students home.

Daniel Slade, Ressler’s lawyer, said in court Wednesday that his client’s plea will cost her the commercial driver’s license she holds, and that she faces the possibility of a six-month jail sentence, $1,000 fine and suspension of her regular drivers license.

“She was revoked by the county to drive a school bus” after she was charged, Slade said, and she has been attending counseling and trying to stabilize a severe respiratory infection before she can be admitted to a 28-day inpatient rehabilitation program.

St. Mary’s District Judge Christy Holt Chesser ordered that Ressler be under the supervision of the state division of parole and probation, and continue participation in an alcohol counseling program, until her sentencing hearing in July.

School officials said Wednesday that Ressler is still a paid contractor with the school system, but that she no longer drives any of her buses.